1. Field of the Invention
The present invention relates to a latch for a motor vehicle door, of the type which is opened electrically.
2. The Prior Art
As is known, present motor vehicle door latches must perform a number of functions which may differ in accordance with the vehicles. These functions are generally performed by a mechanical logic disposed between a retaining system and control means.
The functions to be performed are usually: the opening, the closing, the locking of the latch from the inside and from the outside of the vehicle, and the "child" locking of the rear doors. The points of the mounting of the control means are imposed by, and related to, each type of vehicle.
These mechanical latches have the drawback of being specific to an arrangement of the control means, and therefore to a given vehicle. Consequently, it is advantageous to replace the mechanical logic by an electrical logic which is not related to a given type of vehicle. However, for reasons of safety, an electric latch must remain capable of being operated when the source of current is lacking, i.e. it must be possible to open the door from the interior, and close the door, in such an event.
Known latches having an electric opening system are of a relatively complicated structure and consequently expensive, since they require either means for reversing the supply voltage for the motor or a clutch which is capable of isolating the motor from the rest of the kinematic system of the latch when the latter is open so as to permit the locking thereof upon the next closure.